during his life time. These acquired connections must, of course, very greatly modify the character of the original connections, even though they are made upon the basis of the original connections. There are in man therefore no definite, hard and fast instincts such as characterize the lower types of animals, but rather a complex series of more or less generalized instinctive reactions.
It is evident that the modern psychological concept of instinct, so far from being metaphysical, is wholly biological. The concept of instinct as inborn pathways of nervous currents is the necessary correlate of the biological doctrines of selection and heredity. While the nervous system is more largely modifiable by use than any other part of man's organism, yet its essential structure is inherited and belongs to the stock or the phylum rather than to the individual. The native reactions which are inherited in the hereditary structure of the nervous system are the necessary original equipment with which the individual starts his struggle for existence. Some of these reactions are so simple in organization that they do not enter to any extent into consciousness, and these are known as reflexes. These need not concern us, since they enter directly only into the physical life of the individual organism. But the great majority of these native reactions are complex motor tendencies and have conscious accompaniments, especially feelings, emotions and "desires." Moreover, the acquired habits of the individual, psychologists tell us, are wholly built up through modification of these native reactions. When the instinctive reaction fails to function properly consciousness comes in to adapt the organism to the new situation, the adaptation being made chiefly through the selection from the varied native impulses. All of the habits of the individual therefore rest in the last analysis upon the native impulses. Now, the thesis of this paper is that if instincts are the starting point for man's mental life, they must be for his social life also; if, upon the instincts of the individual, all habits are built, so likewise upon them all social customs, institutions and organization must ultimately rest.
It should be noted that according to the modern psychological concept of instinct, instinctive reactions will vary in different individuals and races. Inasmuch as instinct represents the preformed pathways in the nervous system, made in response to demands of previous life conditions, that is, created by selection, we should not expect to find exactly the same instinctive reactions in the different races of man. Their instinctive reactions, while fundamentally the same, will vary in some degree because the different racial stocks have been exposed to different selective agencies. This explains why race is a factor in social organization and evolution. Again, the two sexes have been created by somewhat different selective and developmental processes; therefore,
- "Response" and "demand" are of course used figuratively, without teleological significance.